<script type="text/javascript">

  var a = 123;
  console.log(a*2);

  var a = '123';
  console.log(a*2);

  var a = '123.50';
  console.log(parseInt(a)*2);

  console.log(a.toString());


  var a = 100/3;
  var b = (a)*2;
  var c = b.toFixed(2);
  console.log(parseFloat(c));

</script>
